Bug 1934612 [wpt PR 49466] - webnn: Support scatterElements in tflite converter, a=testonly

Automatic update from web-platform-tests
webnn: Support scatterElements in tflite converter

There is no TFLite operator to map directly WebNN scatterElements, but
it can be supported with tfl.scatter_nd as the test cases[1] and the
doc[2] described.

The indices also need to be converted like gatherElements.
The update operand must be reshaped to one dimension[3].

[1] https://source.chromium.org/chromium/chromium/src/+/main:third_party/tflite/src/tensorflow/lite/kernels/scatter_nd_test.cc;l=73
[2] https://www.tensorflow.org/guide/tensor_slicing#insert_data_into_tensors
[3] https://source.chromium.org/chromium/chromium/src/+/main:third_party/tflite/src/tensorflow/lite/kernels/scatter_nd.cc;l=64?q=scatter_nd.cc&ss=chromium%2Fchromium%2Fsrc

Bug: 40206287
Change-Id: If0461ceb6c4cb8bcee6ff2b59443851a5cdc7de5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6048693
Reviewed-by: Phillis Tang <phillischromium.org>
Commit-Queue: Phillis Tang <phillischromium.org>
Reviewed-by: ningxin hu <ningxin.huintel.com>
Cr-Commit-Position: refs/heads/main{#1391759}

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wpt-commits: e9d8459f9c413260ace922b865157075bc12b465
wpt-pr: 49466

UltraBlame original commit: 82b7ae37fa53bdab9781d2fe5ac6ef32cf0686ee

Author: marco-c